In addition to looking at current Parkinson’s disease research on this website, I like to look at where technological advances are taking us with regards to future therapies.
In July of this year, I wrote about a new class of engineered viruses that could potentially allow us to treat conditions like Parkinson’s disease using a non-invasive, gene therapy approach (Click here to read that post). At the time I considered this technology way off at some point in the distant future. Blue sky research. “Let’s wait and see” – sort of thing.
So imagine my surprise when an Italian research group last weekend published a new research report in which they used this futurist technology to correct a mouse model of Parkinson’s disease. Suddenly the distant future is feeling not so ‘distant’.
In today’s post we will review and discuss the results, and look at what happens next.
Technological progress – looking inside the brain. Source: Digitial Trends
I have said several times in the past that the pace of Parkinson’s disease research at the moment is overwhelming.
So much is happening so quickly that it is quite simply difficult to keep up. Not just here on the blog, but also with regards to the ever increasing number of research articles in the “need to read” pile on my desk. It’s mad. It’s crazy. Just as I manage to digest something new from one area of research, two or three other publications pop up in different areas.
But it is the shear speed with which things are moving now in the field of Parkinson’s research that is really mind boggling!
Take for example the case of Squalamine.
In February of this year, researchers published an article outlining how a drug derived from the spiny dogfish could completely suppress the toxic effect of the Parkinson’s associated protein Alpha Synuclein (Click here to read that post).
The humble dogfish. Source: Discovery
And then in May (JUST 3 MONTHS LATER!!!), a biotech company called Enterin Inc. announced that they had just enrolled their first patient in the RASMET study: a Phase 1/2a randomised, controlled, multi-center clinical study evaluating a synthetic version of squalamine (called MSI-1436) in people with Parkinson’s disease. The study will enrol 50 patients over a 9-to-12-month period (Click here for the press release).
Wow! That is fast.
Yeah, I thought so too, but then this last weekend a group in Italy published new research that completely changed my ideas on the meaning of the word ‘fast’. Regular readers will recall that in July I discussed amazing new technology that may one day allow us to inject a virus into a person’s arm and then that virus will make it’s way up to the brain and only infect the cells that we want to have a treatment delivered to. This represents non-invasive (as no surgery is required), gene therapy (correcting a medical condition with the delivery of DNA rather than medication). This new study used the same virus we discussed in July.
This week pre-clinical data was published demonstrating that the Ambroxol is active in the brain.
This is important data given that there is currently a clinical trial being conducted for Ambroxol in Parkinson’s disease.
Today’s post will review the new data and discuss what is happening regarding the clinical trial.
Ambroxol. Source: Skinflint
We have previously discussed the potential use of Ambroxol in the treatment of Parkinson’s disease (Click here to read that post). Today we follow up that post with new data that provides further support for an on-going clinical trial.
Firstly, what is Ambroxol?
Ambroxol is a commonly used treatment for respiratory diseases (the respiratory system being the lungs and related components required for breathing). Ambroxol promotes the clearance of mucus and eases coughing. It also has anti-inflammatory properties, reducing redness in a sore throat. It is the active ingredient of products like Mucosolvan, Mucobrox, and Mucol.
What is the connection between Ambroxol and Parkinson’s disease?
So this is where a gene called GBA comes into the picture.
Genetic mutations in the GBA (full name: Glucosylceramidase Beta) gene are the most common genetic anomaly associated with Parkinson’s disease. People with a mutation in their GBA gene have a higher risk of developing Parkinson’s disease than the general population. And interestingly, people with Parkinson’s disease are approximately five times more likely to carry a GBA mutation than healthy control subjects.
What does GBA do?
The GBA gene provides the instructions for making an enzyme (called glucocerebrosidase) that helps with the digestion and recycling of waste inside cells. The enzyme is located and active inside ‘lysosomes‘.
What are Lysosomes?
Lysosomes are small bags of digestive enzymes that can be found inside cells. They help to break down proteins that have either been brought into the cell or that have served their function and need to be digested and disposed of (or recycled).
How lysosomes work. Source: Prezi
Inside the lysosomes are enzymes like glucocerebrosidase which help to break material down into useful parts. The lysosome will fuse with other small bags (called vacuole) that act as storage vessels of material inside a cell. The enzymes from the lysosome will mix with the material in the vacuole and digest it (or it break down into more manageable components).
Now people with a genetic mutation in their GBA gene will often have an abnormally short, non-functioning version of the glucocerebrosidase enzyme. In those cases the breaking down of waste inside the lysosome becomes inhibited. And if waste can’t be disposed of or recycled properly, things start to go wrong in the cell.
How does Ambroxol correct this?
It was recently shown that Ambroxol triggers exocytosis of lysosomes (Source). Exocytosis is the process by which waste is exported out of the cell.
Exocytosis. Source: Socratic
Thus by encouraging lysosomes to undergo exocytosis and spit their contents out of the cell – digested or not – Ambroxol allows the cell to remove waste effectively and therefore function in a more normal fashion. This mechanism of treatment seemingly bi-passes the faulty glucocerebrosidase digestion enzyme entirely.
Until recently, two important questions, however, have remained unanswered:
- Does Ambroxol enter the brain and have this function there?
- What are the consequences of long term Ambroxol use?
We now have an answer for question no. 1:
Title: Ambroxol effects in glucocerebrosidase and α-synuclein transgenic mice.
Authors: Migdalska-Richards A, Daly L, Bezard E, Schapira AH.
Journal: Ann Neurol. 2016 Nov;80(5):766-775.
PMID: 27859541 (This article is OPEN ACCESS if you would like to read it)
In this study, the researchers treated mice with Ambroxol for 12 days and then measured the level of glucocerebrosidase activity in the brain. They gave Ambroxol to three different groups of mice:
- a group of normal mice,
- a group of mice which had been genetically engineered with a specific mutation in their GBA gene (the heterozygous L444P mutation)
- a group of mice that produced human alpha synuclein (the protein closely associated with Parkinson’s disease).
When they looked at the level of glucocerebrosidase enzyme activity in normal mice, they found an increase of approximately 20% (in mice treated with 4mM Ambroxol). One curious finding was that this dose was the only dose that increase glucocerebrosidase activity (1, 3, and 5mM of Ambroxol had no effect). The investigators noted, however, a reduction in water drinking of mice receiving 5mM in their drinking water (maybe they didn’t like the taste of it!), suggesting that they were not getting as much Ambroxol as the 4mM group.
The 4mM level of of Ambroxol also increased glucocerebrosidase activity in the L444P mutation mice and the alpha-synuclein mice (which interestingly also has reduced levels of glucocerebrosidase activity). One important observation in the alpha synuclein mice was the finding that Ambroxol was able to reduce the levels of alpha synuclein in the cells, indicating better clearance of un-wanted excess of proteins.
These combined results suggested to the investigators that Ambroxol is entering the brain of mice (passing through the protective blood brain barrier) and able to be effective there. In addition, they did not witness any serious adverse effects of ambroxol administration in the mice – an observation made in other studies of Ambroxol in normal mice (Click here to read more about this).
These studies have been followed up by a dosing study in primates which was just published:
Title: Oral ambroxol increases brain glucocerebrosidase activity in a nonhuman primate.
Authors: Migdalska-Richards A, Ko WK, Li Q, Bezard E, Schapira AH.
Journal: Synapse. 2017 Mar 12. doi: 10.1002/syn.21967.
PMID: 28295625 (This article is OPEN ACCESS if you would like to read it)
In this study, the investigators analysed the effect of Ambroxol treatment on glucocerebrosidase activity in three healthy non-human primates. One subject was given an ineffective control solution vehicle, another subject received 22.5 mg/day of Ambroxol and the third subject received 100 mg/day of Ambroxol. They showed that daily administration 100 mg/day of Ambroxol results in increased levels of glucocerebrosidase activity in the brain (approximately 20% increase on average across different areas of the brain). Importantly, the 22.5 mg treatment did not result in any increase.
The investigators wanted to determine if the effect of Ambroxol was specific to glucocerebrosidase, and so they analysed the activity of another lysosome enzyme called beta-hexosaminidase (HEXB). They found that 100 mg/day of Ambroxol also increased HEXB activity (again by approximately 20%), suggesting that Ambroxol may be having an effect on other lysosome enzymes and not just glucocerebrosidase.
The researches concluded that these results provide the first data of the effect of Ambroxol treatment on glucocerebrosidase activity in the brain of non-human primates. In addition, the results indicate that Ambroxol is active and as the researchers wrote “should be further investigated in the context of clinical trials as a potential treatment for Parkinson’s disease”.
And there is a clinical trial currently underway?
Funded by the Cure Parkinson’s Trust and the Van Andel Research Institute (USA), there is currently a phase I clinical trial with 20 people with Parkinson’s disease receiving Ambroxol over 24 months. Importantly, the participants being enrolled in the study have both Parkinson’s disease and a mutation in their GBA gene. The study is being led by Professor Anthony Schapira at the Royal Free Hospital (London).
EDITORS NOTE HERE: Readers may be interested to know that Prof Schapira is also involved with another clinical trial for GBA-associated Parkinson’s disease. The work is being conducted in collaboration with the biotech company Sanofi Genzyme, and involves a phase II trial, called MOVE-PD, which is testing the efficacy, and safety of a drug called GZ/SAR402671 (Click here to read more about this clinical trial). GZ/SAR402671 is a glucosylceramide synthase inhibitor, which will hopefully reduce the production and consequent accumulation of glycosphingolipids in people with a mutation in the GBA gene. This approach is trying to reduce the amount of protein that can not be broken down by the faulty glucocerebrosidase enzyme. The MOVE-PD study will enroll more than 200 patients worldwide (Click here and here to read more on this).
The current Phase 1 trial at the Royal Free Hospital will be primarily testing the safety of Ambroxol in GBA-associated Parkinson’s disease. The researchers will, however, be looking to see if Ambroxol can increase levels of glucocerebrosidase and also assess whether this has any beneficial effects on the Parkinson’s features.
So what does it all mean?
There is a major effort from many of the Parkinson’s disease related charitable groups to clinically test available medications for their ability to slow this condition. Big drug companies are not interested in this ‘re-purposing effort’ as many of these drugs are no longer patent protected and thus providing limited profit opportunities for them. This is one of the unfortunate realities of the pharmaceutical industry business model.
One of the most interesting drugs being tested in this re-purposing effort is the respiratory disease-associated treatment, Ambroxol. Recently new research has been published that indicates Ambroxol is able to enter the brain and have an impact by increasing the level of protein disposal activity.
A clinical trial testing Ambroxol in Parkinson’s disease is underway and we will be watching for the results when they are released (most likely late 2019/early 2020, though preliminary results may be released earlier).
This trial is worth watching.
EDITOR’S NOTE: Under absolutely no circumstances should anyone reading this material consider it medical advice. The material provided here is for educational purposes only. Before considering or attempting any change in your treatment regime, PLEASE consult with your doctor or neurologist. Amboxol is a commercially available medication, but it is not without side effects (for more on this, see this website). We urge caution and professional consultation before altering a treatment regime. SoPD can not be held responsible for any actions taken based on the information provided here.
The banner for today’s post was sourced from Pharmacybook
Exciting news recently with the announcement of the Ambroxol study starting.
Exciting for two reasons:
- Ambroxol has the potential to make a major impact in the lives of some people with Parkinson’s disease.
- It illustrates how FAST things are moving in the world of Parkinson’s disease!
Inside each and every cell, there are millions of tiny actions taking place. Minute processes all working in a collective manner allowing the cell to function normally. There are lots of proteins helping to make other proteins, lots of proteins helping other proteins to get to where they need to be, and lots of proteins helping to break down other proteins after they have done their job.
All this activity generates a lot of waste. And a fundamental part of the activity in any cell is waste disposal. If that does not function properly, the cell is in serious trouble.
One of the most common genetic mutations associated with Parkinson’s disease – called GBA – results in cells having trouble getting rid of waste.
Adapted from a cartoon by Dr Jing Pu. Source: The Nichd connection
What is GBA?
Glucocerebrosidase (or GBA) is an enzyme that helps with the recycling of waste. It is active in inside ‘lysosomes‘.
What are Lysosomes?
Lysosomes are small structures inside cells that act like recycling centers. Waste gets put inside the lysosome where enzymes like GBA help to break it down into useful parts. Mutations in the GBA gene can result in an abnormally short, non-functioning version of the enzyme. And in those cases the breaking down of waste inside the lysosome because inhibited.
What is the connection between GBA and Parkinson’s disease?
GBA mutations are the most common genetic anomaly associated with Parkinson’s disease. People with a mutation in their GBA gene are at higher risk of developing Parkinson’s disease than the general population. And people with Parkinson’s are approximately five times more likely to carry a GBA mutation than healthy control subjects.
So what is Ambroxol?
Ambroxol is a commonly used treatment for respiratory diseases. It promotes mucus clearance and eases coughing. Ambroxol is also anti-inflammatory, reducing redness in a sore throat.
Ok, but why the excitement for Parkinson’s disease?
In May of 2014 – less than 2 years ago – this study was published:
Title: Ambroxol improves lysosomal biochemistry in glucocerebrosidase mutation-linked Parkinson disease cells.
Authors: McNeill A, Magalhaes J, Shen C, Chau KY, Hughes D, Mehta A, Foltynie T, Cooper JM, Abramov AY, Gegg M, Schapira AH.
Journal: Brain. 2014 May;137(Pt 5):1481-95.
PMID: 24574503 (This report is OPEN ACCESS if you want to read it)
It was the first time that Ambroxol – a commercially available drug – had been tested in a Parkinson’s disease related context.
In this study the researchers collected skin cells (called fibroblasts) from eleven people with GBA mutations (some had been diagnosed with Parkinson’s disease). They measured the amount of glucocerebrosidase protein and enzyme activity in these cells, and they found that glucocerebrosidase enzyme activity was significantly reduced in fibroblasts from GBA mutations (on average just the enzyme was acting at just 5% of normal levels). They found that ambroxol increased glucosylceramidase activity in fibroblasts from people with GBA mutations AND in fibroblasts from healthy controls. Ambroxol treatment also reduced markers of oxidative stress in GBA mutant cells.
Given the increase in glucocerebrosidase activity after ambroxol treatment, the researchers wondered whether the drug would reduce alpha-synuclein levels in cells that were over-expressing this protein. Amazingly, after 5 days of ambroxol treatment, levels of alpha-synuclein had decreased significantly (15% on average 15%).
You can understand why the researchers were a little bit excited by these results. Here was a drug that re-activated the recycling unit in the cell and reduced levels of one of the main proteins associated with Parkinson’s disease. If the drug can reduce the levels of alpha synuclein in the brains of people with Parkinson’s disease, maybe the researchers will be able to slow down (or even halt) the disease!
Additional studies have now been reported which have confirmed the initial results.
And now the clinical trial?
Funded by the Cure Parkinson’s Trust and the Van Andel Research Institute (USA), it was announced this week that they had started recruiting subjects to be involved in a clinical trial at the Royal Free Hospital in London. The trial is a phase 1 study which will test the safety of Ambroxol in Parkinson’s disease. The researchers will also look to see if Ambroxol can increase levels of glucocerebrosidase and whether this has any beneficial effects in the subjects. The study will be conducted on 20 people with Parkinson’s disease who also have GBA mutations. They will be given the drug and followed over the next 24 months.
These are exciting times for the world of Parkinson’s disease as these drugs are no longer simply reducing the motor features of the condition, but actually attempting to slow/halt the disease.
And as we suggested at the start of the post the pace of these developments is becoming hard to keep up with.